作者: Yahalom-Ronen, Yfat ; Beth-Din, Adi ; Fisher, Morly ; Madar-Balakirski, Noa ; Rosner, Amir ; Stein, Dana ; Steiner, Michal ; Marcus, Hadar ; Tamir, Hadas ; Cherry, Lilach ; Levy, Haim ; Politi, Boaz ; Avraham, Roy ; Madar-Shapiro, Liora ; Yitzhaki, Shmuel ; Vitner, Einat ; Achdout, Hagit ; Nyska, Abraham ; Paran, Nir ; Melamed, Sharon ; Weiss, Shay ; Fatelevich, Ella ; Kronfeld, Noam ; Mechaly, Adva ; Israely, Tomer

BriLife^®, a vector-based vaccine that utilizes the recombinant vesicular stomatitis virus (VSV) platform to express and present the spike antigen of SARS-CoV-2, is undergoing testing in a phase 2 clinical trial in Israel. A nonclinical repeated-dose (GLP) toxicity study in New Zealand white rabbits was performed to evaluate the potential toxicity, local tolerance, immunogenicity and biodistribution of the vaccine. rVSV-ΔG-SARS-CoV-2-S (or vehicle) was administered intramuscularly to two groups of animals (10⁶, 10⁷ PFU/animal, n = 10/sex/group) on three occasions, at 2-week intervals, followed by a 3-week recovery period. Systemic clinical signs, local reactions, body weight, body temperature, food consumption, ophthalmology, urinalysis, clinical pathology, C-reactive protein, viremia and antibody levels were monitored. Gross pathology was performed, followed by organs/tissues collection for biodistribution and histopathological evaluation. Treatment-related changes were restricted to multifocal minimal myofiber necrosis at the injection sites, and increased lymphocytic cellularity in the iliac and mesenteric lymph nodes and in the spleen. These changes were considered related to the inflammatory reaction elicited, and correlated with a trend for recovery. Detection of rVSV-ΔG-SARS-CoV-2-S vaccine RNA was noted in the regional iliac lymph node in animals assigned to the high-dose group, at both termination time points. A significant increase in binding and neutralizing antibody titers was observed following vaccination at both vaccine doses. In view of the findings, it was concluded that the rVSV-ΔG-SARS-CoV-2-S vaccine is safe. These results supported the initiation of clinical trials.

2022-03-15·Analytical Chemistry1区 · 化学

A Novel Quantitative Multi-Component Serological Assay for SARS-CoV-2 Vaccine Evaluation

1区 · 化学

Article

作者: Glinert, Itai ; Afrimov, Yafa ; Mechaly, Adva ; Fisher, Morly ; Ben-Shmuel, Amir ; Abramovitch, Hagar ; Marcus, Hadar ; Manor, Alon ; Madar-Balakirski, Noa ; Fatelevich, Ella ; Bilinsky, Gal ; Lupu, Edith

A multi-component microarray, applying a novel analysis algorithm, was developed for quantitative evaluation of the SARS-CoV-2 vaccines' immunogenicity. The array enables simultaneous quantitation of IgG, IgM, and IgA, specific to the SARS-CoV-2 spike, receptor binding domain, and nucleocapsid proteins. The developed methodology is based on calculating an apparent immunoglobulin signal from the linear range of the fluorescent read-outs generated by scanning the microarray slides at different exposure times. A dedicated algorithm, employing a rigorous set of embedded conditions, then generates a normalized signal for each of the unique assays. Qualification of the multi-component array performance (evaluating linearity, extended dynamic-range, specificity, precision, and accuracy) was carried out with an in-house COVID-19, qRT-PCR positive serum, as well as pre-pandemic commercial negative sera. Results were compared to the WHO international standard for anti-SARS-CoV-2 immunoglobulins. Specific IgG, IgM, and IgA signals obtained by this array enabled successful discrimination between SARS-CoV-2 q-RT-PCR positive (seroconverted SARS-CoV-2 patients) and negative (naïve) samples. This array is currently used for evaluation of the humoral response to BriLife, the VSV-based Israeli vaccine during phase I/II clinical trials.

Vaccines

Development and Validation of a Plaque Assay to Determine the Titer of a Recombinant Live-Attenuated Viral Vaccine for SARS-CoV-2

Article

作者: Girshengorn, Meni ; Epstein, Eyal ; Shmaya, Shlomo ; Adar, Yaakov ; Diamant, Eran ; Lupu, Edith ; Chapman, Shira ; Dor, Eyal ; Toister, Einat ; Cherry, Lilach ; Levin, Lilach ; Monash, Arik ; Zichel, Ran ; Natan, Niva ; Ophir, Yakir

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in more than seven million deaths worldwide. To reduce viral spread, the Israel Institute for Biological Research (IIBR) developed and produced a new rVSV-SARS-CoV-2-S vaccine candidate (BriLife®) based on a platform of a genetically engineered vesicular stomatitis virus (VSV) vector that expresses the spike protein of SARS-CoV-2 instead of the VSV-G protein on the virus surface. Quantifying the virus titer to evaluate vaccine potency requires a reliable validated assay that meets all the stringent pharmacopeial requirements of a bioanalytical method. Here, for the first time, we present the development and extensive validation of a quantitative plaque assay using Vero E6 cells for the determination of the concentration of the rVSV-SARS-CoV-2-S viral vector. Three different vaccine preparations with varying titers (DP_low, DP_high, and QC sample) were tested according to a strict validation protocol. The newly developed plaque assay was found to be highly specific, accurate, precise, and robust. The mean deviations from the predetermined titers for the DP_low, DP_high, and QC preparations were 0.01, 0.02, and 0.09 log10, respectively. Moreover, the mean %CV values for intra-assay precision were 18.7%, 12.0%, and 6.0%, respectively. The virus titers did not deviate from the established values between cell passages 5 and 19, and no correlation was found between titer and passage. The validation results presented herein indicate that the newly developed plaque assay can be used to determine the concentration of the BriLife® vaccine, suggesting that the current protocol is a reliable methodology for validating plaque assays for other viral vaccines.

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